1. Field of the Invention
This invention relates to a semi-automatic umbrella, more particularly to a semi-automatic umbrella with an automatically retractable central shaft.
2. Description of the Related Art
Referring to FIG. 1, an auto-collapsible umbrella as disclosed in Taiwanese Utility Model No. M571657 includes a handle 1, a central shaft 2 mounted on the handle 1, an upper hub 3 secured on an upper end of the central shaft 2, a runner 4 disposed between the upper hub 3 and the handle 1, a rib-and-stretcher assembly 5 connecting the upper hub 3 and the runner 4, and a closing control unit 6. The handle 1 has a push button 101. The central shaft 2 includes a plurality of tubes 201 telescopically fitted to each other and a plurality of spring-loaded rings 202 disposed to retain two adjacent tubes 201 when the central shaft 2 is extended. The runner 4 has a latch 301 disposed to position the runner 4 on the central shaft 2. The closing control unit 6 includes a main spring 601 disposed between the upper hub 3 and the handle 1, a retained block 602 disposed in the handle 1 and connected to the main spring 601, a first spring 603 interconnecting the retained block 602 and a bottom wall of the handle 1, a cord 604 having one end connected to the retained block 602, an actuating member 605 connected to the other end of the cord 604, and a second spring 608 disposed to bias the actuating member 605 downwardly. The actuating member 605 has a large-diameter portion 606 and a small-diameter portion 607.
In use, the runner 4 is moved toward the upper hub 3 by a manual force to extend the central shaft 2 and to permit the central shaft 2 to be held in an extended position by means of the spring-loaded rings 202. The retained block 602 is retained by a retaining portion of the push button 101. The small-diameter portion 607 of the actuating member 605 is engaged with the latch 301 to lock the runner 4 to the central shaft 2.
When it is desired to close the umbrella, the push button 101 is pushed to permit disengagement of the retained block 602 from the retaining portion. By means of the second spring 608, the actuating member 605 is moved downwardly to permit the large-diameter portion 606 to move the latch 301 out of the central shaft 2. Hence, the rib-and-stretcher assembly 5 can be collapsed. By means of the main spring 601, the runner 4 is moved toward the handle 1 to sequentially retract the spring-loaded rings 202 so as to fold the central shaft 2.
However, when opening the umbrella, due to the presence of the main spring 601, a relatively large manual force is required to move the runner 4 until the runner 4 reaches a position where the rib-and-stretcher assembly 5 is totally spread out.